Fwd: Need Help regarding Reading and Writting to a file from kernel function file

[Valdis Kl=?utf-8?Q?=c4=93?=tnieks]

On Tue, 24 Sep 2019 16:10:07 +0900, Sahibzada Irfanullah said:

> subject line. The problem is:  I am trying to write/read page faulted
> physical addresses to a file in a kernel (v5.3-1) function, i.e.,
> handle_ept_violation() which is present in vmx.c. I have followed this
> <https://stackoverflow.com/questions/1184274/read-write-files-within-a-linux-kernel-module>,

Just because somebody on stackoverflow gave a guide doesn't mean it's
a good idea.

What problem are you trying to solve here?  Are you trying to write the faulted
pages themselves to a file?  In that case, just creating the file, using something like
'dd if=/dev/zero of=/your/file/here bs=1M count=4096' and then using mkswap
and swapon will probably work much better.

If you're trying to produce a trace of what pages are being faulted, you can
probably do a better job by using 'perf' to produce trace events with a lot of
added data for you, or use debugfs or netlink and a userspace program to read
the data and write it to disk from userspace.

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